Hermissenda crassicornis

The Opalescent Nudibranch

Phylum Mollusca
Class Gastropoda
Subclass Opisthobranchia
Order Nudibranchia
Family Facelinidae
Genus Hermissenda
Species crassicornis

Description: 4 to 5 cm long, 1 cm wide; body translucent nearly white; slender pointed cerata have a white stripe with orange tips; two white pointed rhinophores protrude from head; neon blue streak runs along body on each side.

Habitat: Mostly intertidal; often found on or around floats, docks and pilings.

Natural History: It feeds on a variety of organisms including acsidians, various eggs, other molluscs, and especially Metridium senile, Mytilus trossolus and hydroids. The nematocysts of the hydroids that it eats are transported to the tips of its cerata where they are used for defense purposes.